Yes, Java can be used for applets, small games etc. But the real power of Java is the ENTERPRISE platforms written in it.
One area where Java is used, quite a lot more than you might think, is in financial transactions. There are companies that run multi-national banking systems using Java in the background, as it scales well and is a robust and reliable platform. A Java-based system is responsible for making sure your credit card transaction is secured and transmitted, often via the internet, to a bank, sometimes in a foreign country, and that the funds are correctly allocated to all the vendors and service providers along the way.
And if you think Java is only for small applications, just take a look at something like NetBeans - almost the entire IDE is written in Java, and that's no small accomplishment. Another use for Java, that you might not even be aware of, is that it is Java that powers BluRay players and devices. Make sure you visit http://worldwind.arc.nasa.gov/java/
to see what NASA is doing with Java as well.
As a professional Java developer, you'd probably spend your day writing complex, multi-user web or enterprise applications that allow users to access these applications remotely via the network. A large part of this development is based on networking, more precisely, the flow of messages and information over the network. Java also makes it easier to write cross-platform applications for mobile devices, so, in theory, you could write an internet banking application in Java and it would work on a wide variety of mobile telephones.
Do yourself a favour and visit this site : http://www.oracle.com/technetwork/ja...sp-142903.html
. It provides a quick overview of some of the Java technologies.
Have fun, in Java, if you aren't having fun, you are doing something wrong!